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    <title>Document</title>
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<body>
   <script>
    //三步完成
    //1 输入用户
    // prompt("请输入姓名")
    //2 内部处理保存数据
    let uname=prompt("请输入姓名")
    //3 打印数据
    document.write(uname)
   </script> 
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